As is known in the art, conventional fuel vapor recovery systems used in automotive vehicles typically include a carbon canister used to recover excess fuel vapor generated in the fuel tank. Activated carbon in the carbon canister adsorbs the fuel vapor and temporarily retains the vapor until the canister is purged. During vehicle operation, at times determined by programmed vehicle calibration, the fuel vapor adsorbed by the activated carbon is desorbed by introducing outside air, or purge air, to the canister. The fuel vapor thus desorbed is fed to the engine for utilization in combustion.
More particularly, automotive internal combustion engines utilize a carbon canister connected to the fuel tank to collect fuel vapors from the fuel tank as the tank is being refilled, or when the vehicle is parked. The canister connected to the engine also allows the vapor stored within the canister to be pulled to the engine for burning during the “purge” cleansing process. Filtered fresh air is necessary for the purging process so that environmental contaminates do not eventually plug the carbon bed or damage some valves which may lead to the generation of On Board Diagnostic (OBD-II) detection faults. An air filtering apparatus with a built-in Canister Vent Valve (CVV) can become an important design element assuring the supply of this clean air.
Filtering of-purge air introduced to a vapor recovery system to purge the carbon canister is not new. For the mentioned purpose, prior art examples teach the use of one or more assemblies comprising either a filter medium, baffle means, or both. More particularly, U.S. Pat. No. 5,058,693 to Murdock et al, U.S. Pat. No. 5,024,687 to Waller, and U.S. Pat. No. 5,638,786 to Gimby each disclose a remote fuel vapor recovery system filter assembly comprising the combination of baffle and filter element means. Both '693 and '687 include simple baffle means comprising no more than two independent baffle entities. The present disclosure discloses a plurality of mating and nonmating planar baffles, the increased complexity of which is matched by increased functional efficiency. Patent '768 provides a self-cleaning air filter comprising a filter element of various embodiments. In each embodiment, this mentioned element, so that it may be cleaned by the disclosure's filter cleaning member, is apparently a thin, firm, screen-like entity, and the filter includes provisions for function upon “occlusion” of this element. The present disclosure is comprised of a robust and hearty (thick, wide and tall) filter element and a baffle area, and has been proven to be able to last the average lifetime usage of vehicles (approximately 150,000 miles) without any cleaning.
There are two primary and novel factors contributing to the long-lasting functionality of our disclosure. The first is found in the design of the baffle section. The plurality of baffles are designed such that the particles, having wide size and inertial distributions, are dislodged from the air stream as it travels from inlet towards the filter section. This occurs due to decreased baffle spacing between baffles and the corresponding increase in mobility demand placed on the air flow. The second primary and novel quality of our disclosure is found in the implementation of a filter element so that the smallest particles (those that survive the baffle section) are generally lodged in the upper half of the filter element and eventually, due to gravity, vibration, etc., will migrate to the lower portions of the element. This occurrence will ensure the thorough cleaning of the air and the long-lasting function of the air filter assembly.
U.S. Pat. No. 4,693,393 to DeMinco et al and U.S. Pat. No. 5,501,198 to Korama disclose examples of filtering systems integrally combined within a carbon canister by comprising only baffle means and only filter element means, respectively. U.S. Pat. No. 5,149,347 to Turner et al also discloses a separator device comprising only a baffle section, which is remotely connected to the carbon canister. It is apparent that any structure comprising only baffle means or only filter means will not be as effective and robust as the present disclosure comprising both baffle and particulate filter means.
U.S. Pat. No. 5,912,368 to Satarino et al., describes a filter that both graduated baffle separation means and filter element means are included in a filter assembly. This assures a maximum degree of separation of particles, foreign matter, such as soot and road dust, moisture, and the like from the fresh air therein otherwise present.